Piezophony



May 27, 1924.

A. McLzNl'coLsoN PIEZOPHONY 2 SheeLs-Sheep i y Filed April 10 1918 May .27, 1924. A M L Nicol-SON 1,495,429

PIEZOBHONY 'Filed April l0, 1918v 2 Sheets-Shleel 2 f/q. Q i i! i J5 J7 J9 Ja 4/ Hq'. /a y ff H 4 fz 4f uw n rATE-NroFr-lCl-z.

ALmANnEn-immfmconsoijos NEW-Yami,- N. Y.,'Ass1eNon :n WESTERN ELEC- 'rmccomnNg-mcoaromrm;en -NEW You, N. Y., A conPoM'rroN o FNEw Ycnmjf -rmzornoNr 1 ,application mee'apririe'ims. Aserial No. sismos.- To all wit-omit :concern: nection with-'the drawings, .in which Fig.

Be it known that I, ALEXANDER MGLEAN 1 illustrates a cross-section' of a piezo-crys- NmoL-som. a sbject' of the King of Great' tal that maybe-employed.; Fig. 2 is a per- Britain, residing .at New York, inthe county s ective of. the-.crystal shown in Fig. 1; 5b G of NewYork'and AState o`New York,'.have igs. 3 and 4 illustrate 3a, crystal provided 'n'vented rtainnew-'iand 'useful Improve- -With electrical-connectionm'Figs; 5, Gand-'7 ments ing'liezophonygof which .the following show. the adaptation of these crystals to loud isa' full, eleartjeoncise; and exact descri-p speakers orv receivers;- Fig-f 8 illustrates a -"tion'. .i 'clvstal-lmounted in a watertight tube and .80 10' As'indi'catlllthe Handbuch der llysik,' a ipt'ed t0 be `ernploy'edf for 4sl'llomarine sig- VOL IV,"'p'.f 774, .190551Piezo-electricity' by naliI1g;-Fig."9' illustrates'a' system employ- F. -Pocl'rfels, "itryvasfrecogized as early as 'ving alpiezelectrical=transintter, repeater 1880 Aluyril.. an `Pf,Curie.that on 'subjecting and receiver; Figa-10 illustrates a repeater i the opposite. sides of certain .crystals `-t0""-circnit'employing piezolelectrie devices; Fig. 65 13'; pressure, adifer'e'ncein .electrical potentialv,11- illustratesthe: adaptation of-a=-1 -ieZ0-'elec at certain- `sidesof-.thecrystal is'jp'roduced'. tric crystal' for carrier current s ignalin `;and f This `diierenee 2in potential was4 'relatively-Fig. I2- illustratesfthe -use ofapiezojlectric 'fsmall 'andi-was determined 'by an-electromcrystal -for detecting miningoperations in. ""eteff' The en -fly"llfVGStgators in the ld' trench warfare. 1 2010ipiezcelectricity 'for pressureelectricity The following very brief/'description wil-1 experimented .with d illerent kinds of `crys` be given fof the. methodjdesoribed in my cotals and observed that this. piezo effect .was pending application, Serial blo-226,343, filed pronounced ina'crystal of sodium potassiuml "Aprilf, 1918, PatentNo'. 1;414,370, Agranted 'tartr at e. Thispriorworkwas entirely ex-l M-a,' 7. 1922,101 preparing a Cryst-al vin 7o 25 lperirnental' and no practicaluse was n iade which the pie'zofelectric effect is very proof 'thisinterestin -phenomenon.` `nounced.` f f According to'te present fnventgion, it has A small crystal of sodium potassium tar-- been discovered that piezo-electric crystals Vtrate,.shown in crosssectionat 1' in Fi ...1, and QSPBC-HYIOSQ 0f Sodium potassium isplaced fina concentrated4 solution lo? its 80 30 tartrate 'are vadmirably adapted or-.uSe-'in mother liquor. This concentrated solution telephone transmitters andA receivers, re-is very slowly cooled and the crystal growspeaters, loud speakers, generators and'modil- `.until itv att-airis'the relative size shown in la-tors ofalternatingcilrrents 'and-the like. the drawing land weighing, in some inlt has beendiscoveredthat .piezo-ele'ctricarl' stancesgy as much` as one. pound. As 'set 85. 33 crystals maybe usedrto particular 'advan-l 'gforth 'in -application 226, 313 referred to tage '1n submarine -signaling orjf'or 'thedel `'above, the crysta1'i's'-preferably supported in tection .of hostile submarines; It. has also th'e motherliquor on aplatform above the been -discovered tliatlthese crystals- When`- bottom-of the.solutiomand'whenso grown placed ontheg'round -or on some' object in tl1e bottoin'o-the crystal will iusually be. 90 i Contact thgthegronnd suchas.- a rock, reentrant, shown-,in Fig. 1, which form` tree, or kthe 'like-',' '-are extremely'. sensitive- Iii i c' re`asesthe"piezo-electriceliectinthe crysto an, earth tremor caused,- for-- ins tancc, by 'ta-1,1 AThe full'fgrowncrystal1is'dried, soaked av pei'sonfwalking'intheproimity'pf. these ,inalcohoI-for"a'fewhours, again dried and crystals. -gj-flhis latter useof these crystals rovided with-j a waterproof coating?A for 9 5 45- ispoi 'particular advan'tage'`in trench-warf instance oiwarff1-he electrical 'resistance An. objectief theinventionis to provide'tal-madelinaccordance with theabove-proc--- piezoelectric devices adaptedtot the .above fess'depends upon r the 'amount' 'of moisture and similar'uses.--a-nd methods 'of loperatingffthatuig 5" the same,as will lne-indicated inthe t'ol- Qtek-alv "-i'noder to stabilizethe .electrical lowingv detailed." description taken in conctmstants'fofthey crystal -itxis provided with rmitted to" enter or lea-vethe erysa waterproof coating such as ambroid or i wax, as lllustrated in Fig. 4.

The electrical 'connections to the crystal may be made by the conductors 4. and (Fig. 3), these being soldered to the crystal b means of the extended surfaces 6 and 7 of oods metal which has a melting oint about the same as that vof the crystal. lectrical connections -are also made to the ,crystal by means of the conductors 8 and 9 l Y foil sheets 11 andthe adjacent 4side of the crystal. This is used to best advantage when considerable electrical power is impressed upon a crystal for instance when it is operatmg as a receiver, the current consumed by the crystal being largely a displacement current.

It is not possible to pre-determine the best manner of connecting the crystal in circuit and this should be determined by trial. `As a rule, onl shown in those two conductors that give the'best 'result may be easil determined. In gener-al, it will be found t. at the best results may be obtained b connecting from conductor 9 to either con uctor 4 or 5, but in other cases best results may be obtained b connecting from conductor 8 to either con uctor 4 or 5. Another arrangement that gives very good results is to connect the conductors 8 and 9 together, usin them as a common conductor nd also emp oying either of the conductors Fig. 5 illustrates a loud speaker, or receiver in which the two crystals 13 and 14 have their'opposite ends fastened to the com- .mon bases 15 and 16. The crystals 13 and 14 may be suitably fastened to bases15 and 16, for instance, by means of the Woods metal,

l' as Ipreviously described.

has been found that a crystal made .as indicated above responds in a greater degree to currents of some frequencies than to currents of othe1-;.f uencies. Each such crystal will in genera have a plurality of resonant peaks depending upon the crystals growth, structure, curing, etc. In some crystals all of .the-Y resonant peakshave been found to lie-in a fr uency zone of 300`to 10,000, and in others t is zone'may lie above 10,000 and extend to 100,000. As there are so manyl factors which determine the frequency characteristics of a crystal, it is dif.- ficult to obtain crystals having identical fre` quency characteristics. It 1s possible to modify the position of thezone of resonance points for instance by varying the period of stal a sheet 12 of a dielectric such.

two of the four 'conductors e igs. 3 and 4 will be used and,

of which has resonant peaks not found in the other. The crystals should be free to vibrate independently and should be connected in series as shown in Fig. 6. It-has been found that this arrangement gives animprovement in the quality of response'as well as an increase in the intensity of response, when employed as transmitters or receivers.

Fig. 6 illustrates a loud speaker or receiver in which the crystals 17 and 1Q at the bottom ends thereof are attached to a common base 19, the upper ends being provided lwith individual bases 20 and 2l.

crystals lshown in Fi 3, 5, 6 and elsewhere.

may be rovided wit a moisture-proofcoatying suc aswax orambroid, as shown in Fi 4. Y

Fig. 7 illustrates a. loud speaker lor receiver in which the crystals 24 and 25 have their opposite ends fastened to the extended surfaces 26 and 27 in a manner similar to tudinally. It is obvious that any number of these crystals may be employed and two are shown only for the purpose of illustration.

Assume a single piezo crystal connected to an electrometer. f a weight is placed on the crystal the variation in compression of the crystal produces an electrification resulting in a 4'deflection of the electrometer needlein a given direction. When the weight is removed the compression is relieved, resulting in a reversal of electrificaticn and likewise of deflection. In this way it is possible to determine the polarity of a crystal; for instance, an electrode of the crystal ma be arbitrarily called a positive -electro e if the removal of the weight produces a positive deflection of the needle when that electrode is connected to a given electrometer terminal. If the devices shown in Figs. 5, 6 and 7 are to operate as transmitters, that is, as generators of current, obviously the crystals should be con'- infinite impedances.

nected in circuit so that the potentials generated will be additive and not subtractive..

If current is supplied to a crystal 1t will.

produce either a longitudinal expansion or contraction of the crystal. -If the devices of. Figs. 5, 6 and 7 are to operate as receivers, preferably when current is supplied to the crystals, they should both expand and contract in synchronism; i. e., when one 'expands the others should also be expanding, so that their eii'ects will be additive for receiver action. As in the case of the transmitter, the proper connection of the crystals may be made either by trial or after predetermining the polarity of the crystals, which are then connected 1n the manner in which lbatteries would be arranged in se*- ries or in parallel.

In the .device shown in Fig. 8, which is adapted to be used for submarine signaling. the crystal 31 has its opposite ends soft soldered to the inside wall of the metal tube 32. The crystal 31 is surrounded by waterproof material such as oil shown at 33, and retained Within the tube by means of stoppers 34.

The operation of the piezo-devices shown v in Figs. 1-8, elther as transmitters or as receivers, will be explained in connection with Fig. 9 in which sound waves impinging upon the extended pole 35 of the crystal transmitter produces a corresponding variable electric current which the transmitter 36 supplies to the repeaterl 37. The vara tions in electric current supplied at the input circuit 38 of the repeater 37 producesa contraction and expansion of the piezocrystal forming a part of this repeater, and this variation in the dimensions of this crystal produces corresponding variations in the electric current supplied to the output circuit 39 of the repeater and these electric currents in* turn produce a variation in the dimensions of the receiver 40, causing its poles 41 to vibrate, thereby reproducing the sounds which were emitted adjacent the transmitter 36.

In Fig. 10 the current produced by the transmitter 42, which is adapted to be actuated by sound Waves, is supplied to the control electrode 43 of the space current device or audion 44. The transmitter 42 is very well adapted to be directly connected to the input circuit of the audion 44 because bothof these have similar andl practically The vamplified currents delivered by the audion 44, which in this case operates as an amplifier, may be connected to the electromagnetic 'receiver -45 or tothe piezo receiver 46.

vice 47 by way of conductors`48 and 49 to i put circuits of the audion 50 are coupled together through the device 47, this circuit will generate oscillations and ,their frequency will be suflicientl'y high for these currents to be employed as carrier currents for radio signaling or for wired wireless. The amplitude of the high frequency current generated is varied in accordance with the sound waves impinging on the device 47, and the modified high frequency irn-` ulses may be delivered to they outgoing line 52.

A piezo transmitter, such as shown in Fig. 8, may be placed in contact with the ground at 53 (see Fig. 1 2) in order to detect earth tremors such as caused by digging for the purpose of placing` a mine. Electrical conductors may extend from the transmitter 53 to .a suitable position in the trench where the receivers 54 are provided.

The invention is not limited to the details of the disclosure, but can be realized in widely different embodiments within the sco e of the claims.

hat is claimed is:

1. A. piezo-electric crystal, a sheet ofv metal adapted to be'fastened thereto, and a dielectric between saidsheet and said crystal.

2. A crystal, and metal having substantially the same melting-point as said crys` -tal soldered to said crystal.

' 3. A piezofelectric crystal and an electrical conductor surrounding said cr stal.

4. A piezo-electric crystal an extended surfaces attached to the opposite ends of said crystal.

5. A telephone instrument comprising .a substance for transforming one kind of 'energy into another, one of said energies being the energy of sound waves, said substance being capable of generating a current in response to a change in pressure.

6. A telephone instrument comprising a crystal of sodium potassium tartrate.

7. A telephone instrument comprising a crystal of sodium .potassium tartrate, and a moisture-proof coating therefor.

8. A telephone transmitter comprising a crystal capable of generatinga current in response to a change in pressure, and a sound receiving element fastened to said crystal. f

9. The combination of means for transforming one kind of energy into another, one of' said energies beinglelectrical and another being acoustical, a space current device having a control member, and a connection between said meansy and said device,

' spouse to a change in pressure. 1

10. The combination of a telephone transmitter comprising Aa crystal' capable of generating a current in response to a change in pressure. an electron discharge device having a control electrode, and a connection between said crystal and said electrode.

11. A piezo-electric crystal having a plurality of faces electrically connected togetber.

12. Means for translating acoustical energy into electrical energy, a space current device having a control member, and a connection between said means and said device, said means comprising a substance capable of generating electromotive force in response to a change in pressure.

13. A wave transforminfr device comprisi1 a substance for trans orming one kind of energy into another, one of said energies being the energyof sound waves, said substance being capable f generating electromotive force in response to a change in pressure.

14. A sound wave transforming device comprising a substance for transforming energy of sound Waves into electrical en-v ergy, said substance being capable of generatlng an electromotive force '1n response to a change 1n pressure.

15. A wave transforming device fory transforming one kind of energy into another, one of said Venergies being the .energy of sound waves, said device comprising' a crystal of sodium. potassium tartrate.

1G. A sound Wave transforming device for transforming the energy of sound waves into electrical energy, said device comprising a crystal of sodium potassium tartrate.

17. A-translator of energy comprising a vpiezo-electric crystal having a reentrant pole-face.

18. A translator of energy comprising a piezo-electric crystal having a principal axis and two axes at right angles thereto, said crystal having a reentrant surface parallel to said principal axis.

19. A wave transforming device for transforming one kind of energy into another, one 'of said. energies being the energy of sound .waves, said device comprising aP piezo-electric crystal having a reentrant' pole-face.

20. A wave transforminv device for transforming the energy ofD sound waves in-to electrical energy said device compris- 'mg a piezo-electric crystal having a reentrant pole-face.

21. A wave transformno' device for transforming the energy ofp sound waves into electrical ener said device compris-` ing a piezo-electri crystal of sodium polective means including a substance capable of generating an electroinotive force in response to a change of pressure.`

23. A whole piezo-electric crystal having a principal axis and twoshorter axes perpendicular thereto, one of said two axes being about four or more times as long as the other.

24. A whole piezo-electric crystal ofsodium potassium tartrate having a princi al axis and two shorter axes perpendicu ar thereto, one of said two axes being about four or more times as long as the other.

.25., The method of operating a body comprising a substance capable of generating electromotive force in response to elastic deformation and capable of the-converse action, said body being resonant at an audible frequency, which comprises elastically deforming said body by t e application thereto of energy waves of a frequency `in the neighborhood of said resonance frequency.

26. The method of operating a body comprising a substance capable of generating electromotive force in response to elastic de` formation and capable of the converse action, whichcomprises elastically deforming said body by the application thereto of ener waves'of an audible frequency in the neig borhood of a frequency of maximum responsiveness of said body and taking olf from said body electromotive force waves of said frequency.

27. In combination., a body comprising a substance capable of generating electromo- Ytive force in res onse to elastic deformation and capable of t e converse action, said body being resonant at an audible frequency and a source supplyin thereto ener waves for caus' elastic ge wavesaving a frequency in the neighborhood of said resonance frequency.

28. In combination a mechanical vibraformation t ereof, said formation and capable of tne converse action, which comprises elastically deforming said body by the application thereto of lenergy.

Waves of a frequency Within theJ voice range, and-taking olf from said body electromotive force Waves the frequency of which is a function of said frequency of deformation.

30. The method of operating a body comprising a substance capable of generating electromotive force in response to elastic deformation and capable of the converse action, which comprises elastically deforming said body at a frequency within the voice .range and taking E from the body electromotive force waves of said frequency of v.deformation.

31. A wave transforming device comprising a substance for transforming one set of energy Waves of an audible frequency into another set of energy waves, said substance being `capable of generating electromotive force in response to elastic deformation and capable of the converse action, and means for translating and utilizing said last mentioned energy waves.

32. In combination, a piezoelectric crystalline body, asdielectric sheet on one face thereof, and means for creating a potential difference between the outer face of said sheet and another face lof said body, said means operating to produce elastic deforma tion of said body.

33. A translator of energy comprising a piezo-electric sodium potassium tartrate crystal having a reentrant pole face.

34. The method of generating elastic vibrations of audible frequency in a medium capable of transmitting them in which a crystal is placed effectively in contactfwith said medium, which comprises generating anelectrostatic field varying in accordance with the frequency of 'the vibrations to be produced, and subjecting said crystal to the action of said varying field.

35. Apparatus for the generation of sound Waves, comprising a crystal, extended elec trode surfaces in proximity to different faces of the crystal, and a source Iof audible frequency alternating current connected to said electrode surfaces. c

36. Apparatus for the generation of sound Waves, comprising a crystal of sodium potassium tartrate, extended electrode surfaces in proximity to different faces yof the crystal, and a source of alternating-current connected to said electrode surfaces.

In witness whereof, I hereunto subscribe my nameV this 2nd day of April A. D., 1918.

ALEXANDER Marmi mcorsou. 

